Synthetic resin hose and method for producing the same

ABSTRACT

A producing method of a hose including, using a mold assembly constituted by a pair of semicylindrical molds each having a large number of intrusion grooves formed along the axial direction in the cylindrical surface of each of the semicylindrical molds substantially at regular intervals and supplying electrically conductive wire into the hose molding mold assembly substantially linearly along the axial direction of the mold assembly; extruding a molten resin tubularly to supply the molten resin into the mold assembly after the supply of the electrically conductive wire; supplying high-pressure air into the inside of the thus extruded molten resin tube to thereby expand the molten resin tube along the corrugated surface of the mold assembly to bring the molten resin tube into contact with the corrugated surface of the mold assembly and, at the same time, making a part of the tube go around to the outer circumferential surface side of the electrically conductive wire along the intrusion grooves of the mold assembly to thereby enclose the outer circumferential side of the electrically conductive wire; cooling the molded resin tube to retain the shape of the tube; and opening the mold assembly so that a hose body integrated with the electrically conductive wire is taken out from the mold assembly.

This is a divisional of U.S. patent application Ser. No. 08/874,739,filed on Jun. 13, 1997, now U.S. Pat. No. 5,944,059, the contents ofwhich is incorporated by reference into the present application.

BACKGROUND OF THE INVENTION

The present invention relates to a synthetic resin hose containingelectrically conductive wire adapted for an antistatic hose, an electriccleaner hose, a reservoir water pump hose, and so on, and a method forproducing the same.

A conventional synthetic resin hose of this type containing electricallyconductive wire is generally configured so that resin-coated rigid steelwire for retaining the shape of the hose and resin-coated electricallyconductive wire for current conduction are helically wound on the hosealong the circumference of the hose, and a hose wall is fitted and stuckonto the outer circumferential surfaces thereof. On the other hand,there is generally known a synthetic resin hose which is configured sothat a wall of the hose is formed of two layers, that is, inner andouter layers, and either one of or both of rigid steel wire and coatedelectrically conductive wire are helically put between the two layers.

As described above, each of the conventional general synthetic resinhoses with electrically conductive wires is configured so that rigidsteel wire and electrically conductive wire are helically disposed overthe whole length of the hose to thereby utilize the strength of therigid steel wire to retain the shape of the hose body.

Accordingly, this kind of conventional synthetic resin hose withelectrically conductive wire has a problem that the weight of thesynthetic resin hose as a whole is heavy, and large fatigue is causedwhen the hose is pulled in use, because rigid steel wire for retainingthe shape of the hose and electrically conductive wire are helicallydisposed over the whole length of the hose.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to solve the problem inthe conventional synthetic resin hose with electrically conductive wire,and to provide a synthetic resin hose with electrically conductive wire,which is configured so that the shape of the hose is retained by use ofthe shape retention of the hose wall per se without use of any rigidsteel wire as a reinforcing wire material and the wiring structure ofelectrically conductive wire is provided as such a special wiringstructure as the electrically conductive wire has substantially thesmallest length and is supported to the tube wall securely without useof any adhesive agent or the like, to thereby attain great reduction ofthe weight of the hose as a whole and form a structure in which fatigueis little even in the case where the hose is pulled in use for a longtime.

The synthetic resin hose according to the present invention in order toachieve the foregoing object includes a tube wall formed corrugatedly ina direction of its axis, and an electrically conductive wire or a coatedelectrically conductive wire disposed over the whole length of the tubewall, in which the electrically conductive wire or coated electricallyconductive wire is disposed substantially straight along the directionof the axis of the tube wall and configured so that the whole length ofthe electrically conductive wire or coated electrically conductive wirein the inner circumferential surface side thereof is covered with thetube wall and the outer circumferential side thereof is enclosedlycovered with peak portions of the tube wall.

Further, the method for producing a hose having such a structure asdescribed above comprises the steps of: using a hose molding moldassembly constituted by a pair of semicylindrical molds each having alarge number of intrusion grooves formed along the axial direction inthe cylindrical surface of each of the semicylindrical moldssubstantially at regular intervals and supplying electrically conductivewire or a coated electrically conductive wire into the hose molding moldassembly substantially linearly along a direction of the axis of themold assembly; extruding a molten resin tubularly to supply the moltenresin into the mold assembly after the supply of the electricallyconductive wire or coated electrically conductive wire; supplyinghigh-pressured air into the inside of the thus extruded molten resintube to thereby expand the molten resin tube along the corrugatedsurface of the mold assembly from the inner circumferential surface sideof the electrically conductive wire or coated electrically conductivewire to bring the molten resin tube into contact with the corrugatedsurface of the mold assembly and, at the same time, making a part of thetube go around to the outer circumferential surface side of theelectrically conductive wire or coated electrically conductive wirealong the intrusion grooves of the mold assembly to thereby enclose theouter circumferential side of the electrically conductive wire or coatedelectrically conductive wire in the part of the tube; cooling the moldedresin tube to retain the shape of the tube T; and opening the moldassembly so that a hose body integrated with the electrically conductivewire or coated electrically conductive wire is taken out from the moldassembly. Incidentally, not only means (blow molding means) forsupplying high-pressure air into the tube but also means (vacuum moldingmeans) for sucking air around the outside of the tube from the outsidecan be used additionally as the expansion molding means for the moltenresin tube.

In the aforementioned synthetic resin hose or in the aforementioned hoseproducing method, the coated electrically conductive wire may be inwhich electrically conductive wire is helically wound on a fiber yarnexcellent in flexibility as an axial yarn and the outer circumference ofthe wire is covered with an electrically insulating material, or may bea wire in which fiber strings excellent is flexibility and electricallyconductive wires are mixed and twisted in the form of a twisted yarn andthe outer circumference of the twisted yarn is covered with anelectrically insulating material. Consequently, it is possible to obtaina synthetic resin hose containing electrically conductive wire which ishardly broken even in the case where bending or contraction andexpansion of the hose is repeated, by use of such an electricallyconductive cable.

Further, in the case where the electrically conductive wire or coatedelectrically conductive cable is used, for example, as an electrostaticinduction line or an earth line in an antistatic hose, the hose may bepracticed as: a hose containing only one line wired; a hose containingone-round-trip lines (two lines) wired as a signal line or a drive powertransmission line or containing two-round-trip lines (four lines) orone-round-trip lines and one earth line (three lines in total)collectively wired in parallel in one place as a signal line as well asa drive power transmission line; or a hose containing those lines wiredsubstantially in two opposite places separately. Further, the syntheticresin material forming the hose wall is not limited specifically butpolyolefin resin represented by polyethylene, polypropylene, etc. ispreferred in terms of good self-restoration against contractivedeformation due to external force.

Further, in the producing method, the structure of the mold assembly maybe formed not only into a structure in which the mold assembly isconstituted by semicylindrical molds each having a large number ofintrusion grooves formed in the cylindrical surface thereofsubstantially at regular intervals along the axial direction but alsointo a structure in which the hose molding mold assembly contains alinear groove formed substantially straight along the axial direction soas to be shallower than the intrusion grooves and independent of theintrusion grooves so that the electrically conductive wire or coatedelectrically conductive wire may be supplied into the mold assemblyalong the linear groove of the mold assembly. The linear groove may bedesigned so that only one electrically conductive wire or coatedelectrically conductive wire can be disposed therein. Otherwise, thelinear groove may be designed to have such a width that not only one butalso two, three or four wires can be disposed in parallel therein.Further, one linear groove may be formed in one place or two lineargrooves may be formed substantially in two opposite places.

Because the synthetic resin hose according to the present invention isconfigured as described above, the hose can be used in the same manneras the conventionally known general synthetic resin hose. Further, inthe case where the hose configured as described above is used as anelectric cleaner hose, a connection pipe to be inserted into andconnected to a joint port of a cleaner operation pipe can be connectedto one end side of the hose, and a connection pipe to be inserted into asuction port of a cleaner body can be connected to the opposite end sideof the hose. The synthetic resin hose according to the present inventionlittle gives a feeling of fatigue to a user so that the hose can be usedwhile keeping a state of less feeling of resistance when the hose isused as an electric cleaner hose attached to a cleaner, because theweight of the hose as a whole is light.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partly cutaway external appearance view of a hose accordingto a first embodiment.

FIG. 2 is a partly vertical sectional side view of an intermediateportion of a tube wall of the hose of FIG. 1.

FIG. 3 is a sectional view taken along line A—A in FIG. 2.

FIG. 4 is a sectional view taken along line B—B in FIG. 2.

FIG. 5 is a partly vertical sectional overall external appearance viewof the hose of the first embodiment having its intermediate portionomitted.

FIG. 6 is a side view showing a state of use of the hose of the firstembodiment.

FIG. 7 is a sectional view of a portion corresponding to FIG. 3, showinganother embodiment.

FIG. 8 is a sectional view of a portion corresponding to FIG. 3, showinga further embodiment.

FIG. 9 is a sectional view of a portion corresponding to FIG. 3, showinga further embodiment.

FIG. 10 is an external appearance view of a portion corresponding toFIG. 1, showing a further embodiment of a hose.

FIG. 11 is a sectional view of a portion of the hose of FIG. 10,corresponding to FIG. 3.

FIG. 12 is a perspective view showing a coated electrically conductivewire.

FIG. 13 is a perspective view showing another coated electricallyconductive wire.

FIG. 14 is a vertical sectional side view of a main part of a moldassembly, for explaining a producing method of the hose.

FIG. 15 is a vertical sectional side view of a portion corresponding toFIG. 14, for explaining another producing method.

FIG. 16 is an external appearance view of a portion corresponding toFIG. 1, showing a further embodiment of a hose.

FIG. 17 is a sectional view of a portion of the hose of FIG. 16,corresponding to FIG. 3.

FIG. 18 is a sectional view of a portion of the hose of FIG. 16,corresponding to FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention will be described belowwith reference to the drawings.

In the drawings, FIGS. 1 through 6 are views showing a first embodimentof the present invention. FIG. 1 is a partly cutaway external appearanceview of a hose body H. FIG. 2 shows a side shape and a centrallysectional shape thereof. FIGS. 3 and 4 show sectional shapes of a tubewall cut along lines A—A and B—B in FIG. 2. FIG. 5 shows an overallshape of a structure as a cleaner hose obtained by omission of anintermediate portion of the hose body H. FIG. 6 is a view showing astate of use of the cleaner hose.

In the synthetic resin hose of the present invention, for example, atube wall 1 is formed of a polyethylene resin tube axially corrugatedlike bellows as shown in FIGS. 1 through 4, and the corrugated shape ofthe tube wall 1 is designed so that the depth of the corrugation islarger than the axial width of each top portion 2 or than the axialwidth of each valley portion 3 as shown in FIG. 2. By this measure,there is obtained a structure in which the shape of the tube wall 1 iseasily self-restored even in the case where the shape of the tube wall 1per se is deformed by external pressure. Coated electrically conductivewires K containing a bundle of copper small-gage wires as anelectrically conductive wire “k” coated with a resin electricallyinsulating material “r” so as to be electrically insulated are made tohave a structure such that they are disposed in two circumferentiallyopposite places of the tube wall 1 so as to extend axially and linearly.As shown in FIGS. 3 and 4, the coated electrically conductive wires Kare disposed so that the whole of each wire K projects inward from avirtual inner circumferential surface of the tube wall 1. The wholelength in the inner circumferential surface side of each wire K iscovered with the tube wall 1. On the outer circumferential side of eachwire K, a portion located in the outside of each valley portion 3 of thetube wall 1 is exposed. In a portion corresponding to each peak portion2 of the tube wall 1, resin materials forming the peak portion go aroundfrom opposite sides of the coated electrically conductive wire K to theouter circumferential surface side so as to abut on each other asrepresented by an abutting line 2 a in FIG. 1 so that the coatedelectrically conductive wire K is enclosedly covered with the resinmaterials.

To use the hose having such a structure as described above as a cleanerhose, after the hose body H is cut into a predetermined length, as shownin FIGS. 5 and 6, a connection pipe 4 for connecting the cut hose body Hto a joint port D in a cleaner operation pipe P is connected and fixedto one end side of the cut hose body H by an adhesive agent, and aconnection pipe 5 for connecting the cut hose body H to a suction port Ein a cleaner body C is connected and fixed to the opposite end side ofthe cut hose body H by an adhesive agent and, at the same time, theelectrically conductive wires “k” of the coated electrically conductivewires K are connected and coupled to connectors 4 a and 5 a in oppositesides.

To use the cleaner hose having such a structure as described above,after the connection pipe 4 in one end side of the hose is inserted intothe joint port D of the cleaner operation pipe P, and the connectionpipe 5 in the opposite end side of the hose is inserted into the suctionport E of the cleaner body C as shown in FIG. 6 and, at the same time,after the respective connectors 4 a and 5 a are electrically connected,a switch S can be operated to be turned on and off.

The frequency of vertical shaking and the angle of vertical bending inuse of the cleaner hose configured as described above are several timesas much as the frequency of horizontal shaking and the angle ofhorizontal bending. Accordingly, if the hose body H is connected to theconnection pipes 4 and 5 while the positions of the connectors 4 a and 5a are taken into account so that the coated electrically conductivewires K are located in opposite lateral sides of the hose body H whenthe clear hose is connected both to the cleaner operation pipe P and tothe cleaner body C as shown in FIG. 6, a risk of cable breaking isconveniently reduced greatly so that the cleaner hose can be used for along time.

FIGS. 7 through 9 respectively show other embodiments of the syntheticresin hose H. The hose H in the embodiment shown in FIG. 7 is configuredso that there is disposed only one coated electrically conductive wire Kfor the tube wall 1. The coated electrically conductive wire K is mainlyused as an earth line. The synthetic resin hose H in the embodimentshown in FIG. 8 is configured so that two coated electrically conductivewires K, K are collectively disposed in one place. Further, thesynthetic resin hose H in the embodiment shown in FIG. 9 is configuredso that two pairs of coated electrically conductive wires K . . . aredisposed in two opposite places of the tube wall 1, respectively.

The hose H in an embodiment shown in FIGS. 10 and 11 is made to have astructure in which only one electrically conductive wire “k” with nocoating is disposed for the tube wall 1 to form a straight line.Accordingly, the electrically conductive wire “k” is configured so thatthe bare wire in the outer circumferential surface of each valleyportion 3 of the tube wall 1 is exposed to the outside. When the hose Hthus configured is used as an antistatic hose, the electricallyconductive wire “k” can be designed to be used as an electrostaticinduction line or an earth line. The hose stated in the presentinvention can be achieved as such a structure.

FIGS. 12 and 13 show examples of the coated electrically conductive wireK, respectively. The coated electrically conductive wire K shown in FIG.12 is formed so that an electrically conductive wire “k” shaped like aflat small-gauge cord or belt is helically wound on a fiber collectiveyarn Y excellent in flexibility as an axial yarn and the outercircumference of the electrically conductive wire “k” is covered with anelectrically insulating resin r. The coated electrically conductivecable K shown in FIG. 13 is formed so that fiber filaments or strings Yexcellent in flexibility and electrically conductive wires “k” are mixedand twisted in the form of a twisted yarn and the outer circumference ofthe twisted yarn is covered with an electrically insulating material.When the coated electrically conductive wire K thus configured is used,the fiber yarn Y serves as a cushion to allow the electricallyconductive wire to expand in the case where a tensile force is appliedto the electrically conductive wire k. Accordingly, the coatedelectrically conductive wire K can be used as an electrically conductivewire hardly broken even by repetitive bending, contraction and expansionof the hose. Accordingly, the coated electrically conductive wire K issuitable as an electrically conductive wire for the synthetic resin hosestated in the present invention.

A method for producing a hose body H configured as described above willbe described below with reference to FIG. 14. Taking into account theconvenience sake of description and the easiness to understand thedrawing, a hose provided with only one coated electrically conductivewire K shown in the embodiment of FIG. 7 will be described.

A mold assembly M shown in FIG. 14 is a mold assembly for a knowntravelling mold type hose molding apparatus in which a large number ofunit molds “m” each having a semicylindrical molding surface areconnected to one another with no ends so that two parts are disposed soas to be opposite to each other. In the molding cylindrical surface ofeach of the unit molds “m” . . . , a large number of intrusion grooves Gare formed substantially at regular intervals along the axial direction.While the mold assembly M is moved forward (left in FIG. 14)successively, the coated electrically conductive wire K is supplied fromthe resin extruder side (right in FIG. 14) into the mold assembly Msubstantially straight along the axial direction in the lower portion ofthe mold assembly M. After the coated electrically conductive wire K issupplied, a molten resin is extruded tubularly from an annular resinextrusion hole formed in a nozzle N of a resin extruder so as to besupplied into the mold assembly M.

At the same time, high-pressure air is supplied into the inside of theextruded molten resin tube t through small holes “h” formed in an airsupply pipe A having an air extraction prevention drum “d” at its headportion and having its base portion fixed to the nozzle N, via an airsupply hole “a” formed in the center portion of the nozzle N so as topierce the nozzle N. If necessary, a suction hole is formed in the moldassembly M so that the tube “t” is sucked. The molten resin tube “t” isexpanded along the corrugated surface of the mold assembly M from theinner circumferential surface side of the coated electrically conductivecable K so as to be forced to abut on the respective intrusion grooves G. . . of the mold assembly M. The tube “t” is further expanded to goaround to the outer circumferential surface side of the coatedelectrically conductive cable K along the intrusion grooves G of themold assembly M and end portions of the expanded tube are brought intocontact with and fusion-bonded to each other so that the outercircumferential side of the coated electrically conductive wire K isenclosed in the portions of the tube “t”. Consecutively, the resin tubeT thus expanded and molded is cooled to be solidified and shape-retainedin the mold assembly M to such an extent that the resin tube T does notget out of shape. Then, the mold assembly M is opened so that the hosethus integrated with the coated electrically conductive wire K isseparated from and taken out of the mold assembly M.

The hose thus molded is a hose having one coated electrically conductivewire K disposed in one place of the hose. It can be understood easilythat the hose shown in the first embodiment is obtained if such coatedelectrically conductive wires K are supplied to two opposite places ofthe mold assembly M. Also, it can be understood easily that the hoseshaving the structures described in FIGS. 8 and 9 can be obtained

FIG. 15 is a view for explaining another producing method. In theproducing method, the structure of the mold assembly M is such that alinear groove “g” shallower than the intrusion grooves G is providedsubstantially straight along the axial direction in addition to theintrusion grooves G formed substantially at regular intervals in theinner surface of the mold assembly M. In this embodiment, the lineargroove “g” is formed to have a depth equal to the sum of the diameter ofthe coated electrically conductive cable K and the thickness of eachvalley portion 3 forming the tube wall 1. Using the hose molding moldassembly configured as described above, the coated electricallyconductive wire K is supplied into the mold assembly M along the lineargroove “g”. The hose is molded in the same manner as in theaforementioned producing method except this point.

The hose thus formed can be provided as a hose with no projection stripeprojecting inward from the inner surface of the hose body H. The depthof the linear groove “g” is not limited to the aforementioned depth butcan be achieved as an arbitrary depth so long as the linear groove “g”is shallower than the intrusion grooves G. Further, the width of thelinear groove “g” is not limited to a width allowing only one coatedelectrically conductive cable K to be disposed therein, and the lineargroove “g” may have a width allowing two or four cables to be disposedin parallel therein. Further, the linear groove “g” need not be disposedin only one place of the mold assembly M, and such linear grooves “g”may be disposed substantially in two opposite places of the moldassembly M, respectively.

The structure of the hose produced by use of the mold assembly M havinglinear grooves “g” formed in two opposite places of the hose is as shownin FIGS. 16 through 18. There can be obtained a hose which contains twocoated electrically conductive wires K, K disposed in two oppositeplaces of the hose respectively and which as a cylindrical innerdiameter with no portion projecting inward from the inner surface of thehose body H.

Although typical embodiments of the present invention have beendescribed above, the present invention is not always limited only to thestructure of these embodiments. Changes of the invention may be madesuitably within the range of the following effect so long as theaforementioned constitutional elements for the present invention can besatisfied and the object of the present invention can be achieved.

As is apparent from the above description, the synthetic resin hoseaccording to the present invention is configured so that a bareelectrically conductive wire or a resin-coated electrically conductivewire is disposed linearly along the axial direction of the hose so as tohave the smallest length with the shape retention of the hose usingeffectively the shape retention of the hose wall per se without use ofany heavy-weight rigid steel cable in the hose body. Accordingly,because the weight of the hose as a hole is reduced greatly, there canbe conclusively expected a remarkable effect that the hose can be usedwith little feeling of fatigue even in the case where the hose is pulledcontinuously in use for a long time.

Further, the method for producing a synthetic resin hose according tothe present invention has an economically remarkable advantage that thesynthetic resin hose having the aforementioned remarkable effect can beproduced by use of a mold assembly used for producing a general bellowshose without any process of producing of novel mold assembly or withoutapplication of any complex process.

What is claimed is:
 1. A method for producing a synthetic resin hosecomprising the steps of: preparing a hose molding mold assemblyconstituted by a pair of semicylindrical molds each having a largenumber of intrusion grooves formed along an axial direction of said moldassembly in a cylindrical surface of each of said semicylindrical moldssubstantially at regular intervals to provide a corrugated surface;supplying an electrically conductive wire or a coated electricallyconductive wire into said mold assembly substantially linearly along theaxial direction of said mold assembly; extruding a molten resin tubeinto said mold assembly after the supply of said electrically conductivewire or coated electrically conductive wire, said electricallyconductive wire or coated electrically conductive wire being positionedbetween said tube and said corrugated surface; supplying high-pressureair into an inside of the extruded molten resin tube to thereby expandsaid molten resin tube along the corrugated surface of said moldassembly from an inner circumferential surface side of said electricallyconductive wire or coated electrically conductive wire to bring saidmolten resin tube into contact with the corrugated surface of said moldassembly and, at the same time, making a part of said tube go around toan outer circumferential surface side of said electrically conductivewire or coated electrically conductive wire along said intrusion groovesof said mold assembly to thereby enclose the outer circumferential sideof said electrically conductive wire or coated electrically conductivewire in said part of said tube; cooling said molded molten resin tube toretain the shape of said tube; and opening said mold assembly so that ahose body integrated with said electrically conductive wire or coatedelectrically conductive wire is taken out of said mold assembly.
 2. Amethod for producing a synthetic resin hose as claimed in claim 1,wherein said pair of semicylindrical molds of said hose molding moldassembly has a linear groove disposed substantially straight along theaxial direction so as to be shallower in depth than said intrusiongrooves; and said electrically conductive wire or coated electricallyconductive wire is supplied into said mold assembly along said lineargroove.
 3. A method for producing a synthetic resin hose comprising thesteps of: preparing a hose molding mold assembly constituted by a pairof semicylindrical molds each having a large number of intrusion groovesformed along an axial direction of said mold assembly in a cylindricalsurface of each of said semicylindrical molds substantially at regularintervals to provide a corrugated surface; supplying an electricallyconductive wire or coated electrically conductive wire into said moldassembly substantially linearly along the axial direction of said moldassembly; extruding a molten resin tube into said mold assembly afterthe supply of said electrically conductive wire or coated electricallyconductive wire, said electrically conductive wire or coatedelectrically conductive wire being positioned between said tube and saidcorrugated surface; sucking air around an outside of said extrudedmolten resin tube to thereby expand said molten resin tube along thecorrugated surface of said mold assembly from the inner circumferentialsurface side of said electrically conductive wire or coated electricallyconductive wire to bring said molten resin tube into contact with thecorrugated surface of said mold assembly and, at the same time, makingpart of said tube go around to an outer circumferential surface side ofsaid electrically conductive wire or coated electrically conductive wirealong said intrusion grooves of said mold assembly to thereby enclosethe outer circumferential side of said electrically conductive wire orcoated electrically conductive wire in said part of said tube; coolingsaid molded molten resin tube to retain the shape of said tube; andopening said mold assembly to that a hose body integrated with saidelectrically conductive wire or coated electrically conductive wire istaken out from said mold assembly.
 4. A method for producing a syntheticresin hose as claimed in claim 3, wherein said pair of semicylindricalmolds of said hose molding mold assembly has a linear groove disposedsubstantially straight along the axial direction so as to be shallowerin depth than said intrusion grooves, and said electrically conductivewire or coated electrically conductive wire is supplied into said moldassembly along said linear groove.